Solution:

Measure in millimeters how far the fainter area extends from the trailing edge.

Select [Machine: Image Quality] in [Advanced Settings] for the custom paper in use, select 1204: [Paper Transfer Output Correction: Paper Edge] and configure the following setting.

In [Trailing Edge Length], enter the value you measured in Step 1 plus an additional 10 mm.

Select [Machine: Image Quality] in [Advanced Settings] for the custom paper in use and record the set values of [Trailing Edge] in 1204: [Paper Transfer Output Correction: Paper Edge].

Increase the scaling factor in the above setting by 10 percentage points.

Print the image. Is the problem resolved?

Repeat Step 5. If the problem persists even though you have increased the scaling factor by 50 percentage points, restore the value noted in Step 3 and go to the next step.

Decrease the scaling factor in the above setting by 10 percentage points.

Print the image. Is the problem resolved?

Repeat Step 8. If the problem persists even though you have decreased the scaling factor by 50 percentage points, restore the value noted in Step 3 and contact your service representative.